1. Field of the Invention
This invention relates generally to an integrated packaging assembly for a monolithic microwave integrated circuit (MMIC) and, more particularly, to an integrated packaging assembly for a MMIC that uses diced semiconductor wafers on which the circuit components are fabricated as the packaging so as to reduce size, weight and cost.
2. Discussion of the Related Art
In actual operating conditions, MMICs are typically enclosed in a sealed packaging assembly. Chip scale packaging is a known technique for environmentally protecting and configuring an electronic chip device and associated circuits within the packaging assembly. A ball grid array (BGA) is one known packaging design that provides an interface to the circuit within the packaging assembly through an array of solder balls mounted to a backside of a base plate of the packaging assembly. The solder balls are electrically coupled to the electronic device and associated circuits within the packaging assembly by electrical vias that extend through a base plate of the assembly. A BGA offers compact size, shortened connector lengths necessary for reducing parasitic capacitances and inductances, and good thermal contact to the packaging assembly for heat sink purposes.
One known application for a packaged MMIC is an antenna front-end circuit for a transceiver associated with a radar system, such as a phased antenna array radar system. A typical antenna front-end circuit that will be mounted in the packaging assembly includes power amplifiers for the transmitted signals, low noise amplifiers (LNAs) for the received signals, phase shifters and digital controllers. For a phased antenna array application, the antenna associated with the transceiver circuit must have a certain scan angle, such as 60°, that determines the dimensions of the packaging assembly in terms of the operating wavelength. As the frequency of the system increases, the element to element spacing and the corresponding antennas size need to be reduced to maintain the same scan performance.
The known packaging material for these types of circuits, such as the BGA discussed above, typically are a ceramic material or like material that enclose the circuit components. The ceramic material adds a significant amount of weight and size to the packaging assembly. A typical BGA packaging assembly for the application discussed above may be on the order of 4 grams, which dominates the overall weight of the array system. In addition, the physical size of the BGA package, limited by mechanical tolerances, yields additional performance constraints, such as reduced scan angle.